This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. CCD camera is routinely used for cryo-EM data collection. However, Quantitative tests for its performance in terms of spectral signal to noise ratio at different frequencies are needed to assess their practical limits.